x-ray tube



E G m L O O n D X-RAY TUBE Filed Oct. 18, 1929 Inv ii Ham D. fiooli His ttm neg.

Patented daily 4, i933 WILLIAM I). COOLIDGE, OF SGHENECTADY, NW7 YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK T-RAY TUBE Application filed Gotober 18, 1929. Serial Ito. 400.691.

The present invention relates to electron discharge apparatus and more particularly to X-ray devices in which the envelope is made partly of metal and is adapted to therad peutic use in body cavities.

X-ray tubes ordinarily comprise bulbous envelopes which contain cooperatin electrodes for producing X-rays. in suc prior devices, the shape and size of the envelope,

M as well as the position of the X-ray producing surface preclude insertion of the X-ray fioducing surface into cavities of the body r internal treatment. An object of the present invention is to provide X-ray appala ratus which is adapted to this purpose.

When treatments are made within body cavities, such as the antrum of the nostril and growths in the throat, etc., it is apparent that the tube ma come into contact with tisan sum or other de icate body surfaces, and for em reason must be constructed to provide facility of cooling as well as to preclude breaks. and'shattering. Accordingly, another 0 ject is to devise a tube construction at which will ofier these advantages without complication of structure. Other objects and features will be apparent as the specification is perused in connection with the accompanying drawing in which Fig. 1 is an elevational t0 view of the im roved X-ra tube and the energizing circuit; Fig. 2 1s a lon itudinal vim: section, partlp broken away, 0 the tube shown in Fi 1; ig. 3 is a sectional view along ine 3-3, Fig. 2; while Fig. 4 W shows the tube about to be inserted into the nostril for one of the special uses to which the tube is adapted.

Referring more particularly to Fig. 1, nu-

meral 1 designates an evacuated cylindrical W lass envelope which terminates at one end in a relatively long reentrant stem member 2 and at the other end in a metallic extension 3 sealed to the glass in the well-known manner. The extension also ma take the form 45 of a cylinder, as shown in ig. 1, which tapers down to a hollow tube 4 of a diameter suficiently small to be inserted into the body cavities. A diameter of one-half inch or less has been found to be a convenient size for most purposes. The end of the tubing remote from the glass envelope is closed and hermetically sealed by a metallic insert 5 which carries, on an interior inclined face, the usual tungsten button 6 constituting an X-ray target. The tube 4 preferably is constructed as a separate member and sealed to the larger cylinder 3 at a flange 7, constituting an ex tension of the latter, the tube being of such length as to extend inwardly of the cylinder for a substantial distance, as shown. There is a metallic focusing cup 55 positioned in o posed relation to the inner end of the tu e 4, the cup containing the usual form of electron-emitting cathode 9 shown as a single turn spiral. The cup 8 and cathode 9 conveniently may be sup orted from the reentrant stem by means 0 a sprin clamp sleeve 10 which fits over the glass to ular member 11. This member is attached to the reentrant stem by a ring seal 12, the stem being extended into the interior of the member 1]. and terminates in a press 13. Current may be supplied to the cathode 9 from a batter 14 three h a pair of conductors 15 whic are scale in the press and connected directly to the spiral at one end and efl'ectively to the other end of the s iral through the focusing cup, as shown. igh voltage may be impressed across the anode 6 and the cathode through a voltage step-up transformer 16; the anode connection may be made to the cylinder 3 or any other suitable place and is grounded for protection. The electrons, upon being emitted by the filamentary cathode, are subjected to the accelerating field of the high voltage and caused to impinge on the target at such a velocity as to produce X-rays. In order to allow the X-rays ready access through the tube 4, there is provided an aperture 17 sealed by a thin window 18 of metal, e. g. resistal (chrome-nickel steel) .6 mil thick. The metal of the window is so thin that it is desirable to copper braze the window to a metal member 19 of invar provided with a flat outer surface and then to silver-solder the member to the tube, as shown more clearly in Fig. 3. During operation, when 10,000 volts for example, are applied across the electrodcs and there is a current drain of about .3 millia npere, the anode 100 [iii tends to become hot and would normall injure the skin or delicate parts of the ody with which the tube 4 may contact, and it is necessary to provide some form of cooling. As exemplified, several turns of relatively small copper conduit 20 may be soldered to the tube 4 in such a manner as to leave unobstructed the window and yet substantiall to cover the entire anode. A coolin flui l; e. g. water, may be pumped throu h t e conduit at a rate to maintain the anode at a reasonably low temperature.

From an inspection of Fig. 4, it will be obvious that the tube 4 may readily be inserted into various body cavities for therapeutic treatment and only the metallic neck portion of the )i-ray devlce is employed for this purpose. The neck portion, being metal, is not subject to fracture and consequently removes this source of danger to the patient and on the other hand, allows a manipulation of the X-ray producing end of the device into the most advantageous position for treatment. The metal portion between the anode and cylinder 3 serves effectively to conduct heat away from the target, hence aiding the cooling conduit in this respect, and to dissipate the heat at a position in the tube where it can do little or no harm. The tube 4 preferably is made of copper but if desired -may be fabricated of nlckel or of some other metal more impervious to X-rays such as platinum in order to prevent skin burn from stray rays or other detrimental effects. It will further be noted that the cathode and anode are spaced a considerable distance apart and that long insulation distanoes' are preserved between the various charged members including the metal envelope so that voltages of a high order may be used, which is of decided advantage in therapeutic work in producing adequate ray intensity. It is obvious that if an X-ray tube of prior art construction and includin a metalhc envelope were reduced in size su ficiently small to be inserted into body cavities, the distance between the envelope and each of the contained electrodes would be so short as positively to preclude the use of hi h voltage.

at I claim as new and desire to secure by Letters Patent of the United States is 1. In an X-ray tube for internal therapy, an evacuated envelope'comprising glass and metal cylinders sealed together, the metal cylinder being tapered down to a tube sufliciently small to be inserted into body cavities, an anode ositioned in thesmaller portion and a cat ode positioned 1n the larger metallic portion.

2. In an X-ray tube for internal therapy, an evacuated envelope comprising glass and metal cylinders sealed together, the metal cylinder being in two connected portions, one of which is of smaller diameter and extends within the other and has a projecting portion of a dimension sufliciently small to be inserted into body cavities, a target positioned at one end of the smaller metal cylinder, a combined cathode and focusing on at the other end of said smaller cylinder an exterior thereto, and a cooling conduit arranged about the tar et.

In witness whereo I have hereunto set my hand this 17th day of October, 1929.E 

